Structure for a voltage detection circuit in an integrated circuit and method of generating a trigger flag signal

ABSTRACT

A design structure for an integrated circuit that includes at least one tunneling device voltage detection circuit for generating a trigger flag signal. The tunneling device voltage detection circuit includes first and second voltage dividers receiving a supply voltage and having corresponding respective first and second internal node output voltages. The first and second voltage dividers are configured so the first output voltage is linear relative to the supply voltage and so that the second output voltage is nonlinear relative to the supply voltage. As the supply voltage ramps up, the profiles of the first and second output voltage cross at a particular voltage. An operational amplifier circuit senses when the first and second output voltages become equal and, in response thereto, outputs a trigger signal that indicates that the supply voltage has reached a certain level.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to the field of voltagedetection circuits in integrated circuits. In particular, the presentdisclosure is directed to a design structure for a voltage detectioncircuit in an integrated circuit and method of generating a trigger flagsignal.

BACKGROUND

In an integrated circuit, analog, digital, or mixed-signal circuits havea range of power supply voltage within which they operate predictablyand reliably. Consequently, integrated circuits typically include apower supply voltage detection circuit for monitoring the power supplyduring its power up sequence. More specifically, during the power upsequence of an integrated circuit, the power supply voltage may takehundreds of milliseconds to reach its desired value. Additionally, thepower supply voltage may ramp up in a non-monotonic fashion, i.e., thepower supply voltage may wobble up and down slightly as it is rampingup, until it reaches a stable desired voltage level. This is becauseduring the power up sequence various circuits activate in sequence andmay cause the demands on the power supply to vary in a nonlinearfashion. Consequently, the voltage detection circuit is utilized todetect when the power supply voltage has reached a certain minimum valueand to generate an electronic indicator (e.g., a trigger flag) to theone or more circuits of interest, which is an indicator that a safeminimum operating voltage is reached.

Traditional power supply voltage detection circuits often trigger off ofmultiples of the voltage threshold (Vt) of a device, such as the Vt of afield-effect transistor (FET) device. In this scenario, when the powersupply voltage reaches a value of, for example, Vt×1 or Vt×2, a triggerflag is generated. However, the Vt of devices changes with process,voltage, and temperature variations and, thus, using a multiple of Vt isnot a stable way to establish a voltage detection circuit. Morespecifically, because the Vt value may vary ±300-450 mV with process,voltage, and temperature, the trigger voltage that results from of astack of transistors, which is used to generate multiples of Vt, mayvary over several hundred millivolts (mV).

For at least these reasons, a need exists for a voltage detectioncircuit in an integrated circuit and method of generating a trigger flagsignal, in order to provide a voltage detection circuit that has a morepredictable and stable trigger flag signal as compared with traditionalVt-based voltage detection circuits.

SUMMARY OF THE DISCLOSURE

In one embodiment, the present disclosure is directed to a designstructure in a machine readable medium used in a design process for anintegrated circuit chip. The design structure includes: a power supplynetwork for supplying a supply voltage to functional circuitry; and atrigger circuit that includes: a first voltage divider stack comprising:a first input in electrical communication with the power supply network;and a first internal node for providing a first divided output voltage;a second voltage divider stack electrically coupled to the power supplynetwork in parallel with the first voltage divider stack and having anonlinear relationship to the supply voltage, the second voltage dividerstack comprising: a second input in electrical communication with thepower supply network; and a second internal node for providing a seconddivided output voltage; and output circuitry in electrical communicationwith the first internal node and the second internal node andoperatively configured to generate a digital trigger flag as a functionof the first divided output voltage and the second divided outputvoltage.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, the drawings show aspectsof one or more embodiments of the invention. However, it should beunderstood that the present invention is not limited to the precisearrangements and instrumentalities shown in the drawings, wherein:

FIG. 1 illustrates a functional block diagram of an integrated circuitthat includes a tunneling device voltage detection circuit forgenerating a predictable and stable trigger flag signal;

FIG. 2 illustrates a schematic diagram of the tunneling device voltagedetection circuit of FIG. 1;

FIG. 3 illustrates an exemplary intermediate node vs. power supplyvoltage plot for various device ratios within a second of two tunnelingdevice stacks of the tunneling device voltage detection circuit of FIG.2;

FIG. 4 is a graph showing the relative tunneling current of high-Vt,normal-Vt, low-Vt and very low-Vt devices as a function of gate voltage;

FIG. 5 illustrates an exemplary trigger voltage plot of the tunnelingdevice voltage detection circuit of FIGS. 1 and 2; and

FIG. 6 is a flow diagram of a design process used in semiconductordesign, manufacturing, and/or test.

DETAILED DESCRIPTION

The present invention is directed to a design structure for a voltagedetection circuit in an integrated circuit and method of generating atrigger flag signal. Referring now to the drawings, FIG. 1 illustratesan integrated circuit 10 of the present invention that may be fabricatedupon an integrated circuit chip 12 and that includes at least onetunneling device (TD) voltage detection circuit 14 made in accordancewith the present disclosure. As described below in more detail, TDvoltage detection circuit 14 generally includes a first device stack 16that includes a first output voltage node V1 having a first voltage thatvaries linearly with a power supply voltage (here, voltage VDD) and asecond device stack 18 that includes a second output voltage node V2having a second voltage (also designated “V2” for convenience) thatvaries non-linearly with voltage VDD. (For convenience, certain voltagenodes and the voltages on those nodes are designated by the samedescriptors, e.g., voltage node V1 has first voltage V1, voltage node V2has second voltage V2, etc.) TD voltage detection circuit 14 may beelectrically connected to one or more logic circuits, analog circuits,and/or mixed-signal circuits (not shown) within integrated circuit 10 asneeded in a particular design. Those skilled in the art will readilyappreciate the variety of circuits that may be used with TD voltagedetection circuit 14. TD voltage detection circuit 14 may also include adifferential operational amplifier (op-amp) circuit 20 and acurrent-mirror circuit 22, and integrated circuit 10 may further includea power network 24, which may be the power distribution network forsupplying an operating voltage (e.g., voltage VDD or any multiplethereof) to, among other circuits, tunneling device voltage detectioncircuit 14. Integrated circuit 10 may be powered by, for example, apower supply 26 that feeds the input of power network 24 withinintegrated circuit chip 12. Power supply 26 may be, for example, anexternal direct current (DC) power supply. Example non-zero steady-statesupply voltage VDD values may include, but are not limited to, 1.0, 1.2,and 3.3 volts.

As described below in more detail, TD voltage detection circuit 14generally operates as follows. When power supply 26 is first started,supply voltage VDD is initially zero volts and then increases to apredetermined non-zero steady-state value. First and second devicestacks 16, 18, which output a linear first voltage V1 and a non-linearsecond voltage V2, respectively, are designed so that at a firstparticular non-zero value of supply voltage VDD, the rising voltageprofiles of first and second voltages cross one another at a secondparticular non-zero value. When op-amp circuit 20 detects this secondparticular non-zero value (by detecting when first and second voltagesV1, V2 become equal, the op-amp circuit may output a trigger flagTRIGGER FLAG to the appropriate circuitry (not shown) that indicatesthat VDD has reached a suitable level to sustain operability ofintegrated circuit 10. A designer may select the first and secondparticular non-zero values of supply voltage VDD and first and secondvoltages V1, V2, respectively, needed for a particular application, anddesign the components of TD voltage detection circuit 14 accordingly.

FIG. 2 illustrates a particular embodiment of TD voltage detectioncircuit 14 of FIG. 1 for generating a predictable and stable triggerflag signal TRIGGER FLAG. In this embodiment, first device stack 16 mayinclude a stack of two similar transistors biased in a current tunnelingmode in order to form a first voltage divider circuit. In one example,first device stack 16 includes n-type transistors N1, N2 electricallyconnected in series between VDD and ground so as to be biased in acurrent tunneling mode. In this example, first voltage V1 onintermediate voltage node V1 is substantially equal to one-half ofsupply voltage VDD. The bulk node B of transistor N1 is electricallyconnected to first voltage node V1, and the bulk node B of transistor N2is electrically connected to ground. In alternative embodiments, firstdevice stack 16 may be formed of a resistor divider network. Inaddition, it is noted that first voltage V1 is not limited to a one-halfof supply voltage VDD; rather, the devices that form the first devicestack may be sized such that first voltage V1 equals any division ofsupply voltage VDD.

In this example, transistors N1, N2 have substantially equal oxidethickness, substantially equal voltage thresholds (Vt), andsubstantially equal oxide areas. The range of oxide thickness is suchthat a tunneling current can flow through each of transistors N1, N2.This range may be about 4.0 nm down to about 0.8 nm. In one example, theoxide thickness of each transistor N1, N2 is 1.40 nm. The range of Vtmay be about 100 mV to about 400 mV, which may be considered a typicalor normal-Vt range for such devices. In one example, the normal-Vt ofeach transistor N1, N2 may be 0.347 V. The oxide area may be expressedin terms of channel width (W) and length (L), measured in microns. Theonly requirement on the oxide area of transistors N1, N2 is that each isat least 1.0 square micron with dimensions of at least 1.0 micron×1.0micron. This condition is to allow the Vt of transistors N1, N2 to beindependent of the variations in the W/L ratio. In one example, the W/Lratio of each transistor N1, N2 may be 50.0/10.0 microns. Because theoxide area of transistors N1, N2 are equal, the voltage acrosstransistor N1 is equal to the voltage across transistor N2 and, thus,first voltage V1 is substantially equal to one-half of supply voltageVDD. Consequently, first voltage V1 has a linear relationship to VDD.

Second device stack 18 may include a stack of two dissimilar nFETs N3,N4 electrically connected in series between VDD and ground and biased ina current tunneling mode in order to form a second voltage dividercircuit. Intermediate voltage node V2 is located between transistors N3and N4. The bulk nodes B of corresponding respective transistors N3, N4may be electrically connected ground. In one embodiment, transistors N3,N4 have substantially equal oxide thicknesses, but have unequal oxideareas and unequal Vts. Like transistors N1, N2 of first device stack 16,the oxide thickness range for transistors N3, N4 may be, e.g., about 4.0nm down to about 0.8 nm. In one example, the oxide thickness of eachtransistor N3, N4 is 1.4 nm.

In the present example and like transistors N1, N2, transistor N3 may beconsidered a normal-Vt device. However, transistor N4 may be considereda low-Vt or an ultra-low-Vt device as compared with each of transistorsN1, N2, N3. A low-Vt range may be considered to be about 0.0 mV to about200 mV. In one example, the low-Vt of transistor N4 may be 0.128 V. Anultra-low-Vt range may be considered to be about −200 mV to about 100mV. In one example, the ultra-low-Vt of transistor N4 may be 0.026 V.Alternatively, transistor N4 may be considered a high-Vt device ascompared with transistor N3. A high-Vt range may be about 300 mV toabout 600 mV. In one example, the high-Vt of transistor N4 may be 0.573V. Because transistors N1, N2, N3, N4 have Vts only a fraction of 1.0V,when power supply voltage VDD is 1.0 volt or less, there is sufficientvoltage margin within TD voltage reference circuit 14 to allow deviceoperation.

Like transistors N1, N2, the only requirement on the oxide areas oftransistors N3, N4 is that each is at least 1.0 square micron withdimensions of at least 1.0×1.0 micron. In one example, the W/L oftransistor N3 may be 130.0/10.0 microns and the W/L ratio of transistorN4 may be 200.0/2.0 microns. Because the Vt of transistors N3, N4 areunequal, the gate tunneling current characteristics of transistors N3,N4 are different and, thus, the voltage across transistor N3 is notequal to the voltage across transistor N4. Consequently, second voltageV2 has a nonlinear relationship to supply voltage VDD and, thus, secondvoltage V2 is not simply equal to one-half of supply voltage VDD.

Op-amp circuit 20 may be a differential operational amplifier circuitfor sensing a difference between two voltages and outputting a signal asa function of this difference. Op-amp circuit 20 may include a standard,high gain, operational amplifier OP-AMP whose negative input is fed byfirst voltage V1 of first device stack 16 via isolation resistor R1 andwhose positive input is fed by second voltage V2 of second device stack18 via isolation resistor R2. Op-amp circuit 20 may also include anoutput circuit 30 that includes the output of OP-AMP and feeds ann-type/p-type pair of transistors N5, P1 whose intermediate node iselectrically connected to an inverter/buffer (INV), whose output, inturn, is a digital trigger signal TRIGGER FLAG. Transistor P1, which maybe controlled by an output of current-mirror circuit 22, which providesa constant current source for transistor P1. The output of operationalamplifier OP-AMP is a voltage level that is equal to second voltage V2minus first voltage V1 and, thus, transistor N5, which is controlled bythe operational amplifier, turns on when the second voltage V2 isgreater than the first voltage V1. Inverter/buffer INV serves totranslate the voltage on the node intermediate to transistors N5, P1 toa clean digital signal, i.e., trigger signal TRIGGER FLAG, that may feedstandard analog, digital, or mix-signal circuitry (not shown). Morespecifically, during the power up sequence, trigger signal TRIGGER FLAGis initially a logic zero and as supply voltage VDD ramps up, triggersignal TRIGGER FLAG transitions from a zero to a one at the instant thatsecond voltage V2 is substantially equal to or greater than firstvoltage V1.

Current-mirror circuit 22 may include a current source 28 that feeds,e.g., an n-type/p-type pair of transistors N6, P2. The output oftransistor P2 is a regulated voltage level that may be used to regulatethe current through a similar pFET device, such as transistor P1.Similarly, the output of current source 28 is a regulated level that maybe used to regulate the current through nFET devices, such as transistorN6. Additionally, current source 28 may provide a current mirrorreference supply for operational amplifier OP-AMP.

The trigger point for op-amp circuit 20 issuing trigger signal TRIGGERFLAG may vary as a function of the N3/N4 device ratio, i.e., the ratioof the respective oxide areas of transistors N3, N4. Therefore, with theoxide area of transistor N3 held constant, the trigger point for triggersignal TRIGGER FLAG may be varied by adjusting the oxide area oftransistor N4, thereby, changing the N3/N4 device ratio. For example,for a trigger point where supply voltage VDD is 1 volt, the N3/N4 deviceratio is set such that the crossover point of the profiles of first andsecond voltages V1, V2 is the desired trigger point voltage divided bytwo, which in this example is 1 volt divided by two, i.e., 0.5 volts.Example N3/N4 device ratios and resulting crossover points of theprofiles of first and second voltages V1, V2 are described below inconnection with FIG. 3, and one example trigger point is described belowrelative to FIG. 5.

FIG. 3 illustrates an exemplary intermediate node vs. power supplyvoltage plot 30, which illustrates various N3/N4 device ratios andresulting crossover points on the profiles of first and second voltagesof TD voltage detection circuit 14 of FIG. 2. In particular andreferring again to FIG. 2, when supply voltage VDD is ramping up,intermediate node vs. reference node voltage plot 30 shows multipleexamples of how there is only one nonzero point at which first voltageV1, which has a linear relationship to supply voltage VDD, and secondvoltage V2, which has a nonlinear relationship to supply voltage VDD,are equal. This crossover point is a function of the N3/N4 device ratioof second device stack 18. The x-axis of intermediate node vs. referencenode voltage plot 30 indicates supply voltage VDD voltage and the y-axisindicates first and second voltages V1, V2.

Intermediate node vs. reference node voltage plot 30 shows a plot of aV1 voltage ramp 32, which in every scenario is substantially equal toone-half of supply voltage VDD because it has a linear relationship tosupply voltage VDD and transistors N1, N2 in this example have identicalvoltages drops. In a first example, intermediate node vs. reference nodevoltage plot 30 shows a plot of a first V2 voltage ramp 34 thatintersects with V1 voltage ramp 32 at a point A, at which first andsecond voltages V1, V2 each equal 200 mV, which is the result of anN3/N4 device ratio of 11.92. More details of the circuit conditions thatgenerate first V2 voltage ramp 34 are shown in Example No. 1 of Table 1below.

In a second example, intermediate node vs. reference node voltage plot30 shows a plot of a second V2 voltage ramp 36 that intersects with V1voltage ramp 32 at a point B only, at which first and second voltagesV1, V2 each equal 300 mV, which is the result of an N3/N4 device ratioof 7.09. More details of the circuit conditions that generate second V2voltage ramp 36 are shown in Example No. 2 of Table 1 below.

In a third example, intermediate node vs. reference node voltage plot 30shows a plot of a third V2 voltage ramp 38 that intersects with V1voltage ramp 32 at a point C only, at which first and second voltagesV1, V2 each equal 400 mV, which is the result of an N3/N4 device ratioof 3.64. More details of the circuit conditions that generate third V2voltage ramp 38 are shown in Example No. 3 of Table 1 below.

In a fourth example, intermediate node vs. reference node voltage plot30 shows a plot of a fourth V2 voltage ramp 40 that intersects with V1voltage ramp 32 at a point D only, at which first and second voltagesV1, V2 each equal 500 mV, which is the result of an N3/N4 device ratioof 2.52. More details of the circuit conditions that generate fourth V2voltage ramp 40 are shown in Example No. 4 of Table 1 below.

In a fifth example, intermediate node vs. reference node voltage plot 30shows a plot of a fifth V2 voltage ramp 42 that intersects with V1voltage ramp 32 at a point E only, at which first and second voltagesV1, V2 each equal 600 mV, which is the result of an N3/N4 device ratioof 2.09. More details of the circuit conditions that generate fifth V2voltage ramp 42 are shown in Example No. 5 of Table 1 below.

In a sixth example, intermediate node vs. reference node voltage plot 30shows a plot of a sixth V2 voltage ramp 44 that intersects with V1voltage ramp 32 at a point F only, at which first and second voltagesV1, V2 each equal 700 mV, which is the result of an N3/N4 device ratioof 1.85. More details of the circuit conditions that generate sixth V2voltage ramp 44 are shown in Example No. 6 of Table 1 below.

TABLE 1 Example circuit conditions and resulting voltages V1 and V2 VDDOxide N1&N2 N3/N4 V1 = V2 Example voltage thickness W/L N3 W/L N4 W/Ldevice voltage No. (mV) (nm) (microns) (microns) (microns) ratio (mV) 1400 1.40 5.0/10.0 130/10  10.9/10 11.92 200 2 600 1.40 5.0/10.0 130/1018.33/10 7.09 300 3 800 1.40 5.0/10.0 130/10 35.71/10 3.64 400 4 10001.40 5.0/10.0 130/10 51.58/10 2.52 500 5 1200 1.40 5.0/10.0 130/10 62.2/10 2.09 600 6 1400 1.40 5.0/10.0 130/10 70.27/10 1.85 700 Note: Inall examples, N1, N2, & N3 are normal-Vt devices and N4 is low-Vtdevice.

Intermediate node vs. reference node voltage plot 30 of FIG. 3 and Table1 illustrate how modifying, for example, the N3/N4 device ratio ofsecond device stack 18 allows the point at which first voltage V1 equalssecond voltage V2 (i.e., the crossover point) to change. In doing so,the trigger point for trigger signal TRIGGER FLAG of TD voltagedetection circuit 14 may be adjusted for a given application.

It is demonstrated in Table 1 that as N3/N4 device ratio is decreased,the intermediate second voltage V2 becomes larger. This can be explainedby the difference in tunneling current of a normal-Vt device versus thatof a low-Vt device at a given gate voltage. A gate current vs. gatevoltage plot 45 of FIG. 4 shows gate tunneling current as a function ofgate voltage for high-Vt (i.e., high-Vt nFET plot 46), normal-Vt (i.e.,normal-Vt nFET plot 47), low-Vt (i.e., low-Vt nFET plot 48), and verylow-Vt (i.e., very low-Vt nFET plot 49) devices. For a given gatevoltage, the current per square micrometer of gate-oxide area increasesas the Vt of the device decreases. It can also be seen that as gatevoltage is increased, this difference between the low-Vt device currentand the normal-Vt device current reduces.

The voltage detection circuit of FIGS. 1 and 2 outputs a flag at a VDDvoltage which is essentially 2× the voltage where first voltage V1equals second voltage V2, and because first voltage V1 is essentiallyone-half of voltage VDD, and the current through device N3 equals thecurrent through device N4, it follows that the voltage across device N3must equal the voltage across device N4, which equals second voltage V2.Hence the gate to source/drain voltages on devices N3, N4 are equal sotheir relative current densities can be found by inspection of thenormal-Vt curve, and the low-Vt curve found respectively in FIG. 4. Thecurrent density of the low-Vt device (N4), is higher than that of thenormal-Vt device (N3), so it follows that device N4 requires a smallerrelative device area for equal tunneling current at equal gate tosource/drain voltages. At higher gate voltages, the difference betweenthe low-Vt device current and the normal-Vt device current is reduced sothe area of low-Vt device N4 must be increased over its value at lowergate voltages. The device ratio of N3/N4 can be adjusted higher or lowerfrom the current density curves of FIG. 4 to chose a trigger voltage ata desired VDD.

Referring again to FIG. 2, example W/L ratios of the transistors of TDvoltage detection circuit 14 that support the W/L values of N1, N2, N3,and N4 shown in Table 1 are as follows: P1=3.0/1.0, P2=3.0/1.0,N5=1.0/1.0, and N6=1.0/1.0.

FIG. 5 illustrates an exemplary trigger voltage plot 50 illustrating theperformance of TD voltage detection circuit 14 of FIGS. 1 and 2. Inparticular, trigger voltage plot 50 of FIG. 5 shows first and secondvoltages V1, V2 ramping up with the power supply voltage (e.g., voltageVDD) and generating a trigger voltage. More specifically, triggervoltage plot 50 shows a power supply signal 52 that is ramping from 0 to2.0 volts, a V1 signal 54 that is ramping linearly from 0 to 1.0 voltsat a rate of about power supply signal 52 divided by two, a set of V2signals 56 (i.e., best case, nominal, and worst case signals) that areramping nonlinearly from 0 volts to respective crossover points A (bestcase), B (nominal), and C (worst case) at which first voltage V1 equalssecond voltage V2, and a set of trigger signals 58 (i.e., best case,nominal, and worst case signals) that transition from a logic zero to alogic one at points D (best case), E (nominal), and F (worst case) alongpower supply signal 52 that correlate to points A, B, and C,respectively. In this example, the desired power supply trigger point iswhere power supply signal 52 equals 1 volt, the W/L of N3 is 130/10, andthe W/L of N4 is 51.58/10, the resulting N3/N4 device ratio is(130×10)/(51.58×10)=2.52, such that the crossover point of first andsecond voltages V1, V2 is approximately the desired power supply triggerpoint divided by two, or 0.5 volts, which results in power supply signal52 voltage values of point D=0.996 v, E=1.070 v, and F=1.131v. In thisexample, the predictability of the transition of trigger signals 58falls in a narrow range of about 135 mV of power supply signal 52.

FIG. 6 shows a block diagram of an example design flow 60. Design flow60 may vary depending on the type of IC being designed. For example, adesign flow 60 for building an application specific IC (ASIC) may differfrom a design flow 60 for designing a standard component. Designstructure 62 is preferably an input to a design process 61 and may comefrom an IP provider, a core developer, or other design company or may begenerated by the operator of the design flow, or from other sources.Design structure 62 comprises circuit 10 in the form of schematics orHDL, a hardware-description language (e.g., Verilog, VHDL, C, etc.).Design structure 62 may be contained on one or more machine readablemedium. For example, design structure 62 may be a text file or agraphical representation of circuit 10. Design process 61 preferablysynthesizes (or translates) circuit 10 into a netlist 68, where netlist68 is, for example, a list of wires, transistors, logic gates, controlcircuits, I/O, models, etc. that describes the connections to otherelements and circuits in an integrated circuit design and recorded on atleast one of machine readable medium. This may be an iterative processin which netlist 68 is resynthesized one or more times depending ondesign specifications and parameters for the circuit.

Design process 61 may include using a variety of inputs; for example,inputs from library elements 63 which may house a set of commonly usedelements, circuits, and devices, including models, layouts, and symbolicrepresentations, for a given manufacturing technology (e.g., differenttechnology nodes, 32 nm, 45 nm, 90 nm, etc.), design specifications 64,characterization data 65, verification data 66, design rules 67, andtest data files 69 (which may include test patterns and other testinginformation). Design process 61 may further include, for example,standard circuit design processes such as timing analysis, verification,design rule checking, place and route operations, etc. One of ordinaryskill in the art of integrated circuit design can appreciate the extentof possible electronic design automation tools and applications used indesign process 61 without deviating from the scope and spirit of theinvention. The design structure of the invention is not limited to anyspecific design flow.

Ultimately, design process 61 preferably translates circuit 10, alongwith the rest of the integrated circuit design (if applicable), into afinal design structure 70 (e.g., information stored in a GDS storagemedium). Final design structure 70 may comprise information such as, forexample, test data files, design content files, manufacturing data,layout parameters, wires, levels of metal, vias, shapes, test data, datafor routing through the manufacturing line, and any other data requiredby a semiconductor manufacturer to produce circuit 10. Final designstructure 70 may then proceed to a stage 71 where, for example, finaldesign structure 70 proceeds to tape-out, is released to manufacturing,is sent to another design house or is sent back to the customer.

An exemplary embodiment has been disclosed above and illustrated in theaccompanying drawings. It will be understood by those skilled in the artthat various changes, omissions and additions may be made to that whichis specifically disclosed herein without departing from the spirit andscope of the present invention.

1. A non-transitory machine readable storage medium containing a designstructure used in a design process for an integrated circuit chip, saiddesign structure comprising: a power supply network for supplying asupply voltage to functional circuitry; and a trigger circuit thatincludes: a first direct current (DC) voltage divider stack comprising:a first input in electrical communication with said power supplynetwork; and a first internal node for providing a first divided outputvoltage; wherein said first DC voltage divider stack is configured sothat the first divided output voltage has a linear relationship to thesupply voltage; a second DC voltage divider stack electrically coupledto said power supply network in parallel with said first DC voltagedivider stack and having a nonlinear relationship to said supplyvoltage, said second DC voltage divider stack comprising: a second inputin electrical communication with said power supply network; and a secondinternal node for providing a second divided output voltage; whereinsaid second DC voltage divider stack is configured so that the seconddivided output voltage has a nonlinear relationship to the supplyvoltage; and output circuitry in electrical communication with saidfirst internal node and said second internal node and operativelyconfigured to generate a digital trigger flag as a function of saidfirst divided output voltage and said second divided output voltage;wherein said second DC voltage divider stack comprises a firstcurrent-tunneling device and a second current-tunneling device coupledin series with one another so as to define said second internal node,said trigger circuit being configured so that said output circuitrygenerates the digital trigger flag as a function of tunneling current ineach of said first and second current-tunneling devices.
 2. Thenon-transitory machine readable storage medium of claim 1, wherein thedesign structure comprises a netlist, which describes the circuit. 3.The non-transitory machine readable storage medium of claim 1, whereinthe design structure resides on storage medium as a data format used forthe exchange of layout data of integrated circuits.
 4. Thenon-transitory machine readable storage medium of claim 1, wherein thedesign structure includes at least one of test files, characterizationdata, verification data, or design data.
 5. The non-transitory machinereadable storage medium of claim 1, wherein said output circuitrycomprises a differential amplifier and an output stage device responsiveto an output stage control voltage, said differential amplifier forreceiving and operating on said first divided output and said seconddivided output so as to output said stage control voltage.